Concentric line cavity resonator device



Sept. 20, 1949. D. vALF'ERT 2,482,452

CONCENTRIC LINE CAVITY RESONATOR DEVICE Filed Aug. 19, '1943 2 sneek-sheet 1 wnNEssEs: y INVENTOR www l m/zf/ fsf/perf.

BY W l' TTR Sept. 20, 1949. l D. ALPERT v 2,482,4/52

CONCENTRIC LINE CAVITY RESONATOR DEVICE Filed Aug. 19, 1945 2 Sheets-Sheet 2 WITNESSES: INVENTUR ATTORNE circuit.

atented Slept. 194

UNITEDsTATEs PATENT OFFICE A Daniel Alpert,-Pittsburgh, Pa., 4assigner to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Applicam gust 19 1943. serial No@ 49am j 8 Claims.

My invention relates to electrical discharge devices in which electrons are projected Ainto electrically-resonant chambers or enclosures, and, in particular instances, relates to devices in which the .enclosures are in the form of what may be called segments ofpa concentric transmission line; that lis to say, the resonant chambers comprise a substantially concentric inner and outer conducting cylinder, the annular spacing between the two being closed by conducting end walls. The projection of electronsinto such resonant chambers may, by suitably disposing and proportioning the circuit elements, be caused to generate high frequency electrical oscillations Vor alternatively to abstract power from a supply source to accelerate the electrons to ex-V tremely high velocities. SuchA arrangements may be referred toas devices ofthe monotron v powerful electrical standingwaves therein.

Another object of my invention is to provide an arrangement by which electrons projected into a resonating chamber of the concentric line type maybe made to supply electrical oscillations of extremely'high frequency to an external Still another object of my invention is to provide an electrical oscillation generator forextremely short electric waves which' shall be adapted to provide va Arelatively large electron current,Y flowing from an electron-emissive source of a comparatively large area into a resonating.r

chamber.

l A still further'object of my invention is to provide an electrical oscillation generator in which electrons from a source are projected into aL resonant chamber which shall be capable of a high conversion eliciency of power from a direct current source to the alternating current power.

A still further object Vof my invention is to provide a structure for oscillation generators which make use of electrons projected into a resonating chamber 'in which the `chamberitse1f shall be divided into two portions with the electron flow confined to one portion ymaintained at a high vacuum, while other portions of the resonating chamber are at atmospheric pressure and may contain induction loops and other circuit and power transmission elements.

vide a high Vfrequency. electrical generator in which electrons are projected intoa resonating chamber which has'the form of a cylinder with areentrant central portion at one end, whereby an electric field into which electrons are' projected increases in intensity as the electron proceeds.

Still another object of 'my invention is to provide an Velectrical discharge'device in which electrons are projected into the interior of a resonating rchamber which has substantially the shape of the cavityk between segments of two concentric spherical surfaces.

A further object of my invention is to provide an electrical Vdischarge device in which electrons or other electried particles may be accelerated to extremelyrhigh velocity by passing through the resonating chamber wherein they abstract energy from an alternating electric field mainf tained in existence in the chamber. .Other objects of my invention will, become apparent upon Vreading the following descrip tion taken in connection with the drawings, in which: Y, f

Figure 1 is a vertical section; Fig. 2 is a section along the line II-IIr in Fig. 1 of one type of electric oscillation generator employing a resonating chamberrof the concentric-line type; ,A -V p Y Y Fig. 3i isa section cna diametral; plane ofl a structurally Amodified form of an oscillation gen- Still another object of my invention is to pro# 55.

eratc2 r yof the general type` disclosed in Figs. 1 and ;,V s Y* v Fig. 4 isa section on a diametral plane of an oscillationgenerator of a type somewhat similar to that of Figs. 1 and 2; but in whichthe concentric-line resonating chamber 'is provided with a reentrant portion;

Fig.- 5 is a section on a diametral plane through still another type of oscillation generator Vin which the resonating chamber has the form of a cylindrical cavity having a'centrally disposed reentrant portion;

Fig. 6 is a vertical 'section through an oscillation generator in which the resonating chamber has the form of thespace intervening between segments of two concentric sphericalsurfaces;

Fig. 7 is a'horizontal section through'an electrical discharge 'device in which electrons are projected through a resonating chamber of the concentric-line type to impinge upon an X-ray tremely high velocities;

nating field of which the electrical component' is radial, and the magnetic component'comprises circles concentric with the cylindrical axis. frequency of this mode of 4vibration is primarily determined by the length Il, aliengthea 's this length L being one-half the wave lengtnin `the case of the fundamental modeof vibration.

In accordance with the form-of: my invention TheV 4 by rings of an alloy comprising substantially 18% cobalt, 28% nickel and the remainder iron. In the middle portion of the outer cylinder 3 are provided perforations 'l forming what might be termed a grid through which electrons may be projected into the chamber I in a radial direction. Attached` by vacuum-,tightseals to the DlOjeClJng edges. 6 is an` annular structure 8 of glass such as Corning 4Glass Co.s G705AJ or other suitable vacuum-tight insulating material,

VThe chamber I and the annular enclosure B thus forrnla vacuum-tight enclosure which may be 'maintained at a high degree of vacuum.

VlSamperted onfleals 9 sealed into the glass shown in Figs. 1 through 4, electrons generatedexternal to the outer cylindrical surface and giving a substantially radially-inward velocity are projected through .suitable grids or openings in the youter cylindrical wall. It is found'that electrical vibrations will set up in the mode described above in the interior of the annular chamber and that, in consequence of such vibrations, some of the electrons will be acceleratedv by this electric eld, for example, during a one-half cycle thereof, while those electrons following during the succeeding one-half cyclel will be retarded` As a result, the first-mentioned' set of electrons maintain an average velocity higher than the second set, as a consequence of which the electrons tend to become bunched together, and the stream within the chamber to comprise a flowof alternately high and low electron concentration. It is possible to show that if theVtransit time ofthe bunched electrons lbetween-the outer and inner cylinders is of the values "11A, 2`1/4, or generally n+1@ (where n is any integrer) cycles ofthe above-mentioned fundamental' mode of vibration of the chamber, these electronsV Willreach the inner cylinder with Ya velocity substantially less than that With which ltheyy entered it. In consequence of this, the electrons give up vpart of the energy they had on entering the chamber to the alternating electric field within the resonating chamber and Ythus maintain energetic oscillations therein. f

Since the electric eld varies inversely in lpro- I portion to the radial'dist'ance from the central axis of the cylinders, thisleld increases in intensity as the electrons proceed toward the'inner cylinder. As a result of this increasing concentration of the electric eld as-theelectrons proceed, it is possible to'insure an almost complete halting of the radial motion of the electrons-,- thereby attaining-a high efficiency o'f conversion of electrical energy from the direct 'currentsource' which sets up the electric eld which originally accelerated the electrons outside the chamber to the electrical energy of the electrical vibrations within the cylinder.'

With the foregoing principles in mind, it may` be stated that Figs. l'and 2 show a chamber I having walls comprising an inner cylinderf.,l and a concentrically disposed outer cylinder 3 having the annular spaces` between them. closed by two annular end walls 4 and 5. All of the abovementioned chamber'walls are of conducting inaterial; for example, they may be of copper. 'The outer cylindrical wall 3 has projectingV edges 6 comprising a metal whichlsuccessfully seals with some suitable insulating material, such as glass. For example, the projecting edges maybe formed wan a is an anrma'r'cathode Il in the form of anannular metal member having a U-shaped cross-section open on its radially-inward side. Within the member II is positioned an electrical heater I2 which may, for example, be in the form of a helix, fed from a local source with electric current through` one pair of iin-leading wires 9. The radially-inward faceof the member II is closed by an annular metal member I3 which has its radiallyinward face coated with a mixture of barium and strontium or other suitable thermionically-emissive material. The two limbs of the U-shaped member Il"projec`t slightly inward beyond the electron emissiveface of the member I3 to form Whenheated an electronemissive source which tends to focus electrons and project them through the perforations 'lV the cylindrical face 3. This focusing action may, if desired, be supplemented by auxiliary projecting members I4 lwhich may be electrically connected to the U-shaped member II or, if preferred, maybe insulated therefrom and provided with means vfor maintaining them at a desired electrical potential relative to the member II. The helical heater I2 may be insulated from the surrounding U-shaped member II by quartz blocks-spaced at suitable intervals around the circumference of the annular member II. If desired, these quartzblocls may be provided with a trough-like depressionin which the heater element I2 securely rests. The precise form of the therimonically-emissive structure I I, I2 I3, I4, is amore or less` optional feature of my invention, and any other suitable arrangement known tomen skilled in the art may be substituted therefor. The electron-emissive surface I@ is maintained at a sufficient negative potential relative to thev cylindrical wall 3 byl a suitable external voltage source I5, so that the electrons emitted from'` the surface I3, when the element I2 is electrically heated, are projected at substantial velocity throughrthe perforations'l into the chamber I. In one wall, forexample, ofthe chamber I is provided an insulating bushing I6 through which a lead wire I'Iv adapted to be connected to an external circuit passes into the chamber I, wherein it is ybent up to form` a loop with its end electrically connected to thechamber I.

IIfhe velocity with which electrons enter chamber I through yperforations 'I which is preferable. for insuring the maintenance of electrical vibrations within the chamber may be calculated, in accordance with the relationship pointed out above, as follows. The periodicA time of the electric vibrations corresponding to a wave-length equal to 2L, Where L is the distance from plate 4 to plate 5,- is

where C is vthe velocity offlight. The velocity of anelectron having atransit time; over the vdistance d from' `cylinder 3 to cylinder 2 whichv equals 111+ lljcycles of lthis periodic time 'is The structure just described is evacuated by methods tooV wellknown'in the Velectron tube art to require descriptionV here, and thereafter main# tained ata suitable nigh vacuum. (when electrons accelerated by thepotential diiierence betweeny the chamber I and the emitting surface I3 areprojectedzthrough the perforations 1 into the'chamber I, theyfall under theiniiuence of any electrical eld therein,'such, for instance, as exists when this chamber isv electrically vibrating, for example, in its fundamentalv inodehaving the electric eld projectingiradially from cylinder 2'to the cylinder `3.' If'nec'essary to initiate vsuch vibrations, electric Acurrents'of the 'necessary'` freduency may be impressedfon the in-leadingwire 1I1'to start the generationlof high vfrequency oslcillations, in thefc'hamber I howevensuch initial stimulation willv usually not befound necessary to` start oscillation of the chamber I. The method and Yreason for .generation of oscillations 'within' -the chamber I and,v upon theout-leadingfcon- 'ductor I1 having'beenexplained before, it' is not believed necessary to expatiate upon the method of operation of the device shown in Figs. land 2. The method of myv invention shown ,inv Fig. v3 is more suitable than that shown in Figs. 1and12 'for certain purposes. It comprises an inner conductive cylinder 32 and an outer conductive cylinder 33, which are interconnected With each other by walls 34, 35, of glass orA other suitable vacuum-tight insulating'material. The walls 34 and 35 may be sealed 'tothe cylinders 32 and 33 by welding vto the latter .suitable rings`36 of the alloy mentioned in connection WithFigs. 1 and V2. The wall 33 is provided with perforations 31similar tothose in wall 3 described lin Fig. 1, and there is likewise provided athermionically enis sive 'cathode 4I, 42, 43, ,44, substantially identical with that described in Fig. 1. `Thecathode structure 4I, 42, 4 3, 44, is enclosedwithin an annular glassr'nember 4 5 which may be sealed'tosuitable ringsA 46 of the alley already. mentioned `which arevvelded to the cylinderI 3.

V,Respectively above and, below the glass walls 3,4 and'areprvided apair of annular'conduct ing AI;ro'ugh `-.like members 41, 48 which v-t v with reasonable. closeness .into ,the annular space 'l'oe-` tween the cylindeisz and 33' Through an ns'ulating bushing 49V a lead wire 50 maybe brought into the space between the-member 48 and the -glass wall 35, whereitis bentoverintotheIorm of aloopadapted to transmit; vibrations to a load circuit asin the manner of the lead wire I1V in Fig. 1. The arrangement in Fig., 3, comprising the members 41 and 48 which-are detached from and move relative to theglasswalls-34 and 35, has the advantage of .-permittinga variation at will4 of vthe distance L between them which, as

y previously stated fixes the resonantfrequency of the oscillations generated within -the chamber bounded by wal1s 32, 33, 41, 48. Y f- Fig.- 4 shows -a structure for .oscillation generators which is similar to that described inconnectionwith Figs. 1and2, except as regards the shape ofthe conducting walls oftheresonating chamber. In Fig.A 4 the resonating chamberl 5| has as its interiory face what may be described as. iylleril Perlion .5 2` which is expandedffor :aeertalnidistance.midway of `the axis, to form-a larger cylindrical or reentrant portion 52. The

advantage, forcertain purposes, of providing the `reentrantportion 52 in the inner cylindrical wall -is"=thatitiresults in-a more rapid `concentratiori of .thel electric field within the chamber,` as the electrons vmove radially inward after they pass through perforations 53 inthe external wall 54 o'f .the reentrant chamber. Since the l annular glass enclosure55 for the electron source 56,51,

58,' 56 is 'substantially the same in nature as the elements II, I2, I3, I4 in'Figs. l and 2, it is be# lieved that ndfurther description of Fig. 4"is necessary here.

Fig. y5 shows amodified forml of oscillation generator in which the direction of projection of the electrons into the resonating chamber is parallel to the -central axis (which is vertical in Fig. 5) instead of radial, as in theV modifications sofar discussed. The resonant chamber6I com'- prises `'an external conducting cylindrical wall 62 closed at the top by conducting end plate 63 which has' a central projecting portion 64, preferably 'of cylindrical shape.` The base of the resonant chamber 6I comprises a conducting plate 65 hav ing a central yarea somewhat larger in diameter than the cylindrical projection 64 above mene tioned, which isA filled with perforations 66 through which electrons may lbeprojected into chamber 6I. Below the perforations 66 is positioned a cathode 61 comprising Ya circular plate coated with therniionically emissive materials, and preferably provided with an upturned edge portion which extends toward but doesv not quite contact the plate 65.- Surrounding and projecting slightly beyond the edges of this edge portion is a conducting ring 68, at which the plate 65 may, if desired, be attached by supporting 'insulators 69. vThe conducting ring 68 and' the base plate 65 are supported from anv insulating foundation 10. Inleading wires 1I, 12 are pro"- jected by which the plate 65 may be maintained at a suicient positive potential relative to 'the cathode 61, to accelerate and'project-"electrons emanating therefrom through thefperforati'ons 66. `The conductingring 68 may, if; desired, 'be connected directly to thefcathode 7611, rlnitfor some purposesit will be found desirable to p rovide it with an inleading wire 13, by which it may be maintained at afparticularly potential adapted to more eilectively focus electronsemanating from *thev cathode 61 upon the perforations 6,61 An electric'heater 15 is provided by-'whichi-the cathode. 61 may be'maintained in a thermionically-emissive condition. 2 '.-When the resonant chamber 6I is set in vibra tion,v the electrical field willhave substantially the conguration indicated by the broken lines 16. In 'some portion vof the walls of the resonant chamber'II, for example, in the wall 63 not far from the central cylindrical projection 64 is positioned an insulating bushing 11 through which an inleading wire 18, forming a loop within 'the chambenmay conduct electric' energy to external circuits through Ya concentric line* 19; l A.As in thecaseofthe former rescn'ator'shown in Figs. 1 to 4, the potential impressed on the plate es reiativetozthe cathode si-islsuenfaslto cause vthe 'electrons passing through the perforations sa to enter the chamber sl with suchave'- locity, that the time theyrequire -tofreach'fthe projection 64 is n+1@ cycles of theafundamental mode of vibration of the chamber sLYwnicnnas the electric eld distributionrepresented by the brokenlines 16.1. '-Whenthis adjustment is-made,

f The chamber 9| has a mode' of electrical vibrav tion in which the lines of electric force are substantially radial, and when electrons enter ythe chamber 9| through fthe-perforations |0|- they will be 'acted upon by this electric iield, and their velocity at the time they' reach the periorations |02 can be shown todepend upon the values of this -electric'eld,and the length* of vtime which the electrons spent in traversing the path between perforations and perforations` |02. Some `of the-'electrons passing through the perforations |0|-wil1 be'acceleratedrby the electric eld s0 that the time thatr theyA spend intraversing the pathv between |0| and |02 will be less than that corresponding Ato the velocity 'with which they entered the perfo'rations |0|, while others of these electrons will be retarded and traverse the path between the perforations I0| and |02 with a lower velocity. Asa result, the faster electrons will tend to overtake therslower electrons, and there will bea bunching effect in the yelectron streamemanating vfrom the perforationsfl02. If the exit energy of the electrons,emanating from the perforations |02 is plotted against the time each'electron entered perforations |0|, it can be shownthat a curve similar to Fig. 9 will result V space between the perforations|02 and' |03,`since it does not form a vportion of the electricallyviy brating chamber 9|, and it cank be shown that the Aenergies and hence the translation ,velocities of certain of these electrons will be further increased as they traverse the space between the perforations |03 and- |04, where they are again acted upon by the oscillating electric eld within the resonant vspace 9|.f Certainof zthe original electrons `Will-accordingly enter ther-.cylinder 91 with ahigher velocitythan that to which they had attainedwhen they left the cylinder .96.. They source which maintained the resonant oscillations within the chamber' 9 sincethose electronswhi-ch, reach grid |02 with energy4 less .than E cause vsuch resonant oscillations of chamber 9|. to be maintained. To take a s'pecic instance, it can be shown that the energy-ofy the electrons emanating from the perforations |04 maybe increased to V500 Vor 600 kilovolts, y whereas their energy onlentering the perforations |0| was only 100 kilovolts. Y y f Y f.

vIt is, of course, desirable that of thegelectrons emanating from the perforations |02,. only;'the high velocity ones should pass through the perforations |03 and continue onward ultimately vto impinge upon the anode 85. This selection of high velocity electrons may be effected by providing a magnetic field in the interior of the cylinder 92 having a direction parallel to the axis thereof. A magnet core ||5 excited with direct current winding IIS may be provided for this purpose. It can be shown by calculations well known to those versed in the electronic art that the electrons passing through such a field will follow curved paths, the radius of curvature in any particular path depending upon the velocity of the Y electrons traversing it. Thus, by locating the perwhere ordinates represent energy of the electrons l."10 Y forations |03zinithe -vval'lof cylinder 92'in a position .correspondingvtoi the paths, -of Vhigh velocity electrons-through cylinder 92,. and Vleaving `the Wall of cylinder 92r solid at the terminus of the paths of lower velocity'electrons, it 1 can be insured that vonly "the @high velocity electrons emanating *from the perforations 02' will pass through the perforationsi|03 to enter the chamber-9| for the second time. The magnetic deilecting eld above-mentioned `should be substantially limitedto'the interior of the cylinder 92'; if this-is done vthe electrons 'emanating from the perforations '|03 into thechamber 9| will thereafter traverse straight line-paths across the latter; Theposition oi'the cylinder 91 and the perforations I'Mshouldfo'f course, correspond to th'eterlnins'on th'ewall'ofcylinder 93 0f the paths'just' mentioned.

Another possible' menige-6finsuring that @my the 'fastest 'electrons emanating fomperforations |02 shall: reach'theperforatio'ns |03 would beto insert a vgrid with 'ahighn'egativ potential Arelative to'the'walls of the cylinder 92 midway in the path of thei electrons V'between*perforations V |02 and |03. In such casethefperforations'|02, |03', |04 Aand anode |05'shnuldline up with the'rectilinearpath of electrons projected bycathode |06 through perforations I 0 Such a grid would turn back the slowerlelectrons emanating from the perforabions. 1| 0.2;? .and allS .them .ultimately Y t0 imping'e'onthe 'cylinder-'92," but would permit .'hishnougn to pass A A the 'grid to reacqulre velocity :and'jleave theperfora. ions |03 with the but'these'principlsiare capabley ofrapplication in many alternative farms whicnwlmibe evident to thpseskilledin the art.A Forv example, I have described ele'ctron's'. 'as the. electried" particles projectedint'o .the resonating chambers, but' it will be. ei/identit@ .those skiued'infthe art that subs'tantially .any 'elt'ectrii'led body may replace them, the relationbfetween their entrance velocity .and the dimensions ofi the ,resonating chamber .being substantially-.the sainev as ,described forV electrons.

Also other forms 'of resonating'. chamber and other have in fact abstracted energy from the current modes ofvivbr'ation id. agotheridirections fcrgthe alternating electricgield) maybeemployed provided thefelectried particles are projected with a, velocity, component` along .this iield.V

I claim .as invention: f V- 1. lAn electrical discharge device comprising a chamber having conducting .walls in the form of an outer cylinder havingperforations in its wall and v`an. unperforated Vinner .cylinder interconnectedat each end by. electrically conducting materal, an electron emissive source .positioned adjacent tosaid perforations.,andfinsulated from said walls, and means vincluded by said device for impressing an,electric.field-in'the'V region adjacent said source ,for projecting electrons lfrom s aid source through said perforations into said chamber.

2, An electrical discharge device comprising a chamber having conducting walls in the form of an outer cylinder having an annular band of perforations in its wall and an inner cylinder interconnected at each end by electrically conducting material, an electron emissive source positioned adjacent to said perforations and insulated from said walls, means included by said device for impressing an electric field in the region adjacent said source for projecting electrons from .l1 source: through midi into said clnannsbery .and couplings means ai portion .projecting Within said .chxmherior transmitting energy resident am deotrieeid inm'desaid .to a work;

3'; Arr electrical: discharge. device comprising a chamber having` conducting wallsin. the farmaci an `outer cylirnierv having an band on perfcrations in its walt and an inner cylinder interconnected; at each end by eiectricaliy een;- ducting material= an. electron. emissive source, sitioned adiacenti; to said pertomtions and; in.- suiated said chamber, a vacumnftight en.- .closure maintained at a high vacuum. enclosing said source andes/id perforatiorm, and `Irreansinfeluded bysaid. device tor' inapremng an. electric nel-d inthe region acl-acont saidsource for pro-- jecting electrons from said sonrce through said. pertorations intofsaid chamber.

4. An electrical discharge. device. comprising a..l chamber having conductmawadls mthe form oi an outer cylinder having Vperforations in its Wall. and an unperorated cylinder iizniercon-l nected ateach end vby electrically conducting material, an electron emissive scmrcaf positioned adjacent to said periorations. and insulated from said. chamberr a vacuum-tight .enclosure main` tained atv a high vacuum enclosing, `said cathode and said perforatinns, means included by deviceior impressing an electriceld in the regian. adjacent said source tor projecting, electrons irom said source throughisaid Vperforations into said chamher.and coupling means .having a portion projecting within said chamber for transmitting energy residentinan electric. :deld inside. said chamber to a work circuit..

5. An electrical ,discharge device comprising a chamber having conducting Walls, inthe form of' an outer cylinder having .a perforated area in its wall and an inner cylinder interconnected at each end by electrically conducting material; said area subtending a maior portion of the circumference. oisaid outer cylinder, a linearly extending electron emitter subtending said perforated area, means. included by saiddevice for impressing an electric eld in the region'adjacent said source forl causing electrons.. from. said source toile projected through said pertoratons into said chamber, and means. having a, portion ,projecting `within sad chamber for utilizing the Venergy' of electrical oscillations produced withinsaid chamber.

6". An electrical discharge device comprising a chamber having conductive 4Walls in the form of anouter cylinder havingperforations in its walls and an. inner cylinder interconnected at. each end emissive source, positioned .adjacent to said perforations and lnsulatedfrom said chamber, means included by said device for impressing an'el'ectric field in the region adjacent said source for projecting electrons from .said source through said perforations into saldi chamber, the radial dis'- tance between said. inner vand sadfoutercylinders being such that said electrons traverse it ina Y by electrically conducting material, an electron y 12 time. equal toi w+ t/ii. cycles of the.` fundamental modezot electrical; vibration ofsaidl chamberwhere n.. is any integer.

T. An; electricai discharge device comprising; a cheminer: hav-ine conducting' wal-ls in the form. of anouter" cylinder having periorations in; its walls and anrinner cylinder interconnected at each end hy'pmtes: of electrically conducting materiaLan electron emissive source positioned adjacent to. saidperforations and insulated` from said chan-1.F included by' said device.I for impressing an eiectricneld inthe region adjacentsaict source tor projecting; electrons from said, source through perforations into said` chamber, said. elec.- trons passing? through said perforaticcsisl with a velocity which is substantiallyl v where. a is. the radial distance. from the innerer saidcylinders. to. the outer of said.'cylinders4 L. is the distance between said. plates, c is the velocity oi light, .and 1.1.V is any integer.,

V8` .An Velectrical discharge device comprising a. chamber having, conducting Walls. in the form. oi an outer cylinder having. a. perforated area in its.

wall `and an inner cylinder interconnected'. atA

each end by plates. of. electrically conducting, ma.- terial). said area subtending a maior portion of the circumference of said outer cylinder, a linear` ly extending electron emitter subte'nding4 said perforated area., means included byv said device for. impressing an electric. eld inthe region adjacent said source forA causing electrons from. said source, to, be projected through said perforations into. said chamber, and means coupled to a member .projecting into said chamber for utilizing the energy of electrical oscillations produced Within said chamber, said electrons passing through said perforations a velocity which is equal to 'Die of patent:

UNITED STATES EA''ENTSl Number 'Name Date 2,170,2i9' Seiler Aug. 22, 1939 2,190,668 Llewellyn Feb. 20, 12949 2,259,690 p Hansen et al. Oct'. 21,1941 2,320,866 Fremlin' June 1^, 1943 2,368,031V Llewellyn Jan. 231V i945 2,372,213 VLitton Mar. 2T, 1945- 2,409,694' Laid'g Oct. 22, i946 

